Abrasive wheel.



CLARENCE ROSCOE KING, OF WORCESTER, MASSACHUSETTS, ASSIGNOB TO NORTON COMPANY, A CORPORATION OF MASSACHUSETTS.

ABRASIVE WHEEL.

No Drawing.

To all whom it may concern:

Be it known that I, CLARENCE Roscoe KING, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Abrasive Wheel, of which the following is a specification.

This invention relates to an abrasive wheel and particularly to that class of porous abrasive wheels in which a silicate binder is employed to unite the particles of abrasive material and to hold them firmly together. A

It is the principal object of my invention to improve the construction of such wheels in such manner that their efficiency will be thereby greatly increased.

More specifically, my invention consists in the addition of a supplementary bond to an abrasive wheel of the type above defined, this bond in its preferred form being composed of one of the synthetic resins. Other features of my invention willbe hereinafter described and more specifically pointed out in the appended claim.

An abrasive wheel of the type defined is usually made by mixing loose particles of abrasive material with some form of silicate binder, the mixture thus formed bei'ng molded into the desired shape and size and being thereafter hardened by the application of heat. In their commercial form such wheels are commonly classified as vitrified wheels and silicate wheels.

In the case of the vitrified wheels, the silicate binder takes the form of clay, together with other mineral silicates, which are partially fused when burned in a potters kiln, and thus form a porous mass partaking more or less of the nature of porcelain or glass and firmly uniting the grains of abrasive material into a unitary structure.

In the formation of the silicate wheels the principal binding constituent is silicate of soda, commonly known as water glass. This silicate is mixed with the loose grains of abrasive material and with certain mineral powders. After being molded to the desired shape and size, this type of wheel is dried and is then heated to a sufficient temperature to cause the silicate of soda to react with certain of the other minerals in:

cluded in the combination and to thus become fused into a hard, porous mass which securely holds the abrasive grains in place.

Snecification of Letters Patent.

. between the wheel and the work.

Patented July 31, 1917.

Application filed. May 28, 1914. Serial No. 841,677.

Each of these two types of wheels thus utilizes some form of silicate binder for securing the abrasive material in place and they are both characterized by the unitary, porous structure of the finished wheel. It has been heretofore supposed that the porous condition of the wheel was very essential for efficient grinding, and that the relation established between the voids and the grains was one of the important factors in deter mining the efficiency of the Wheel.

When a wheel of this type is in use, the grains of abrasive material upon the surface of the wheel are subjected to severe strains caused by impact and torsion, in addition to the abrasive or grinding action As the efficiency of the wheel depends largely upon the ability of the binding material to resist these strains, the development of the greatest possible mechanical strength in the binding material is of the utmost importance.

The silicate bonds formed in the manner above described may, for practical purposes, be considered as thin envelops inclosing he abrasive grains, and in this condition they are not resilient nor do they possess any large degree of tensile strength.

I have discovered that by filling the voids of the porous structure of the abrasive wheel with a supplementary bonding material of a particular character, I can largely remedy the deficiencies of the silicate binder with respect to resiliency and toughness and can thereby secure greatly increased efiiciency in operation.

v In the preferred form of my invention, as at present practised, I utilize one of the so-called synthetic resinsas the supplementary bonding material. These resins are manufactured under various trade names, such as bakelite, condensite, amberoid plastic, fenoforci, and the like, and have in common the property of receiving a permanent set when heated to a moderate temperature. Havin once received this set they cannot again fie liquefied by any temperature ordinarily encountered in grinding operations. Broadly speaking, they may be distinguished from the mineral or silicate bonds by the designation organic.

In the formation of my improved abrasive wheels, I form the wheel in the usual manner as herein described, and then immerse the wheel in a solution or liquid containing one of these synthetic resins. the voids of the porous wheel are filled with the solution, E subject the wheel to a sufficient degree of heat to give the synthetic resin a permanent set.

l Vhen thus treated, "the resin solidifies to a hard and tough substance which supplements the regular silicate binder and greatly increases the strength or" the wheel as a whole. Wheels thus treated not only remove more material per unit of wheel wear, but they also act as they would have done it they had originally been made several grades harder. Wheels to which the supplementary bond has been applied have been proved by actual tests to wear from two to four times longer than the same wheels without the additional bond.

While my invention is of great value in all classes of wheels using a silicate binder it is of especial value for wheels in which silicon oarbid is the abrasive material. In these wheels it is necessary that the silicate binder should take the form of a porcelain bond, and it has heretofore been impossible to make these wheels as hard and porous as can be made with an aluminous abrasive material and a glass bond. By the use of the supplementary bond, I am enabled to so strengthen the porcelain bond that a coarse silicon carbid wheel may be made much harder and will last much longer than was previously possible.

While I have described the use of a supplementary bond composed of one oi synthetic resins it do not wish to be limits thereto, as it is evident that the results herein described may be obtained by the use of any material as a bond which can be applied in such form as to fill the voids of a porous wheel and which can thereafter be given a permanent set by the application of heat thereto. Furthermore, while I have described my invention as embodied in a grinding wheel, it is evident that the principles thereof are equally applicable to a grinding or abrading instrumentality 01 any other "form, and I do not limit my invention to any particular form of grinding device.

Having thus described my invention; what I claim as new and desire to secure by Letters-Patent is,-

An abrasive wheel comprising particles of abrasive material united by a silicate binder to form a unitary porous structure, and having the voids thereoffilled with a supplemental bond composed of a synthetic resin which is in liquid form when applied to the wheel and which possesses the property of changing under the action of heat alone to a permanently solidsubstance insoluble in water and having a melting point higher than the temperatures attained in ordinary grinding operation.

In testimony whereof I have hereunto set my hand, in the presence of two subscribing witnesses.

CLARENCE ROSCUE KING.

Witnesses:

fines. T. Hawnnr, C. Fonensr Wesson. 

